酸性菜地土壤中钝化剂对镉的钝化效应研究

Effects of Amendments on Cadmium Passivation in Acidic Soils with Vegetable Production

在土壤与农产品重金属污染问题日渐加剧的背景下,开展菜地重金属污染土壤修复和降低蔬菜重金属超标风险成为亟待解决的问题。为探究钝化材料在酸性土壤上的适用性及有效阻控蔬菜吸收土壤中镉(Cd)的潜力,选取3处(T1、T2、T3)酸度不同的菜地,设置5种钝化剂(粉煤灰、钙基膨润土、镉康、海泡石和生物质炭)和5种主要市售蔬菜(白菜、甘蓝、莴笋、紧花菜和散花菜)开展田间试验,研究不同钝化剂对酸性土壤中有效态Cd含量及蔬菜Cd含量的影响。试验结果表明:钝化剂显著影响菜地土壤理化性质。钙基膨润土对土壤Cd具有显著钝化作用。海泡石对蔬菜Cd吸收过程有明显的阻控效果。通过对蔬菜镉富集能力的聚类分析,可将5种蔬菜分为低富集(紧花菜、散花菜、白菜、甘蓝)和高富集(莴笋)两类。主成分分析显示蔬菜Cd含量与土壤总Cd和有效态Cd含量呈正相关,与土壤p H呈显著负相关。施用钝化材料(生物质炭、海泡石)并结合蔬菜品种筛选是降低酸性菜地土壤重金属污染风险,确保蔬菜安全生产的有效措施。

With increasing heavy metal pollution in soil and agricultural products,it is urgent to take actions to remediate heavy metal-polluted soils with vegetable production and reduce the risks of heavy metal pollution in vegetables.In order to explore the applicability of different amendments on acidic soil and their potential in inhibiting absorption of Cd from soil by vegetable,vegetable field experiments were carried out in three different fields with varied pH(T1,T2 and T3).Five amendments(fly ash,calcium-based bentonite,cadmium-kang,sepiolite,and biochar)and five popular commercially available vegetables(chinese cabbage,cabbage,lettuce,compact cauliflower,scattered cauliflower)were investigated in field experiments to study the effects of different amendments on the concentration of available Cd in acidic soil and the Cd concentration in vegetables.The results showed that amendments significantly affected the physical and chemical properties of vegetable soil.Calcium bentonite had clear soil Cd passivation effects.Sepiolite obviously inhibited Cd absorption in vegetables.The five vegetables can be divided into low enrichment group(compact cauliflower,scattered cauliflower,chinese cabbage,cabbage)and high enrichment group(lettuce)in terms of Cd absorption capacity based on cluster analysis.Principal component analysis showed that the Cd concentrations in vegetables were positively correlated with total Cd and available Cd in soil,and significantly negatively correlated with soil pH.To conclude,using suitable amendments(biochar,sepiolite)in vegetable production systems with low Cd enrichment capacity is an effective measure to reduce the risks of heavy metal pollution and ensure the safe production of vegetables in acidic soil.